What will be the definition of confirmation time and data used for
I would appreciate confirmation.
I believe the data presented on blockchain.info's site is collected by the following method:
This chart reports the median time for transaction confirmation, but note that it excludes any transactions with zero fee.
It is potentially worth noting that some transactions are published with a low time preference, meaning the person initiating the transaction may intentionally include a low fee that will take a while to confirm, and this would drive the 'average confirmation time' up, even though the network is functioning well for it's users.